The invention relates to a pneumatic spring pot, comprising a pot wall, a bottom connected to the pot wall and a first annular flange opposite the bottom and connected to the pot wall.
The invention relates, furthermore, to a method for producing a pneumatic spring pot of the abovementioned type.
Such a pneumatic spring pot is part of a pneumatic spring system which is used in motor vehicles for the spring suspension of the superstructures or body.
The pneumatic spring pot, as a structural part of a pneumatic spring system, has the function of providing an air volume. A further function of the pneumatic spring pot is, at one end, to ensure the tie-off of, for example, a pneumatic spring concertina or other pneumatic spring components, for which purpose the pot wall is connected correspondingly to an annular flange narrow in diameter. A bottom is connected to the pot wall at that end of the latter which is opposite the annular flange, in order to tie the pneumatic spring pot up to the body, for example by means of threaded bolts. A further function of the bottom is, for example, to receive the damper bearing and, as a result of this, to absorb damper forces. In the installed state of the pneumatic spring pot, the bottom forms the upper end of the pneumatic spring pot and the annular flange for the fastening of, for example, the pneumatic spring concertina forms the lower end of the pneumatic spring pot.
The pneumatic spring pot known from DE 199 07 656 A1 has a first supporting part and a second supporting part, between which the pneumatic spring concertina is fastened. The two supporting parts each have a bottom, a pot wall and an annular flange, these abovementioned parts as a whole being formed in one piece with one another from sheet metal. The production method for the two pots serving as supporting parts is not described in the document. Furthermore, the bottom is not suitable, either in the first supporting part or in the second supporting part, for serving as receptacle for a damper bearing.
A further pneumatic spring pot is known from the German book “Fahrwerktechnik: Stoβ- und Schwingungsdämpfer” [“Chassis Technology: Impact and Vibration Dampers”], 2nd Edition, Vogel-Buchverlag, Würzburg 1989. This pneumatic spring pot has a bottom, a pot wall and an annular flange for fastening a pneumatic spring concertina, the bottom, pot wall and annular flange again being formed in one piece from sheet metal.
The bottom of this pneumatic spring pot has an orifice, through which a piston rod is led, the damper bearing or head bearing being arranged as a separate structural part of the bottom. There is therefore no integration of the head bearing housing or damper bearing housing into the pneumatic spring pot, this leading to a generally complicated overall form of construction of the pneumatic spring system.
Pneumatic spring pots constructed at least from two parts are also known. A first part in this case consists of the bottom and of a portion of the pot wall, and the at least second part consists of the remaining portion of the pot wall and the abovementioned annular portion. These two parts are connected to one another by means of an assembly method, conventionally by means of welding. A pneumatic spring pot of this type is known, for example, from DE 100 50 028 A1.
In the two-part design of the pneumatic spring pot, the two individual parts are manufactured, as a rule, as drawn parts which are subsequently assembled by welding. The disadvantage of the at least two-part design of the pneumatic spring pot is, however, that the number of operations required and therefore the outlay in terms of time and cost in the production of the pneumatic spring pot are increased.
However, because of the narrowing in diameter of the annular flange at the concertina start, it is not possible for a generally one-part design of the pneumatic spring pot with bottom, pot wall and annular flange to be implemented to the desired extent of the narrowing in diameter in one and the same sheet metal forming methods, for example in a deep-drawing method.
This is also, inter alia, because, normally, a further annular flange for the damper bearing is already integrally formed onto the bottom of the pneumatic spring pot and projects away from the bottom in the same direction as the annular flange at the opposite end.
The known multipart design of the pneumatic spring pot with the at least two pneumatic spring pot parts being welded together has the further disadvantage that the manufactured pneumatic spring pot subsequently also has to be sealed by being surface-treated, for example with a lacquer. For even when the pneumatic spring pot is produced from an initial material which has received surface treatment, for example galvanization, this surface treatment is destroyed at the weld seam due to the welding. In order to avoid corrosion of the finished pneumatic spring pot, therefore, the pneumatic spring pot has to be sealed once again, at least in the region of the weld seam.
In the known pneumatic spring pots constructed from two deep-drawn parts welded to one another, a supporting ring was additionally also required in order to tie the pneumatic spring concertina to the annular flange, so that the annular flange does not collapse owing to the high pressure force of the pneumatic spring concertina. To be precise, the pneumatic spring concertina is fastened to the annular flange with a high pressure force, in order to avoid an undesirable detachment from the pneumatic spring pot during the operation of the pneumatic spring system.
It will be conceivable, in principle, to manufacture a pneumatic spring pot of the type initially mentioned in one piece from the solid material by lathe-turning. Since manufacture of the pneumatic spring pot by turning from a solid material entails a very cost-intensive high outlay in terms of material and time, the method of this type is not suitable for large series manufacture.